I had a MiniSIM in my old Motorola Defy. I went in to a Vodafone shop and they switched the miniSIM for a new SIM that was MiniSIM in size, but had a MicroSIM popout. When my moto G arrived I just popped out the MicroSIM. Doing that is free, and it includes all your contacts and stuff that is stored on your old SIM.

If you order a Moto G it would be worthwhile doing the swap early so you are all ready to go when the Moto G arrives.

It's a decent device, seems quite fast. The camera seems ok. The bezel's quite large, top and bottom especially, but sides as well. Overall it does feel like a budget device (high end budget device) mostly because while build quality is good it's not comparable to more expensive phones. The S4 looks and feels like a much higher end device, but it does cost around 3x more. It will do my fiance for a good while though I think, and if she wants something better it can be a good backup phone for us.